<StructLayout(LayoutKind.Sequential)> Structure MIDIHDR
        Public lpData As Int32
        Public dwBufferLength As Int32
        Public dwBytesRecorded As Int32
        Public dwUser As Int32
        Public dwFlags As Int32
        Public lpNext As Int32
        Public Reserved As Int32
    End Structure
 
    <StructLayout(LayoutKind.Sequential)> _
    Structure MIDIEVENT
        Public dwDeltaTime As Int32 ' Ticks since last event
        Public dwStreamID As Int32 ' Reserved - must be zero
        Public dwEvent As Int32 ' Event type and parameters
        Public dwParms() As Int32 ' Parameters if this is a long event
    End Structure

Declare Function midiStreamOpen Lib "winmm.dll" ( _
                                                          ByRef phms As Int32, _
                                                          ByRef puDeviceID As _
                                                          Int32, _
                                                          ByVal cMidi As Int32, _
                                                          ByVal dwCallback As _
                                                          Int32, _
                                                          ByVal dwInstance As _
                                                          Int32, _
                                                          ByVal fdwOpen As _
                                                          Int32) As Int32
 
 
    Declare Function midiStreamClose Lib "winmm.dll" (ByVal hms As Int32) As _
      Int32
 
    Declare Function midiStreamOut Lib "winmm.dll" (ByVal hms As Int32, _
                                                    ByRef pmh As MIDIHDR, _
                                                    ByVal cbmh As Int32) As _
                                                    Int32
 
    Declare Function midiStreamRestart Lib "winmm.dll" (ByVal hms As Int32) As _
      Int32
 
 
    Declare Function midiOutPrepareHeader Lib "winmm.dll" ( _
                                                              ByVal hMidiOut As _
                                                              Int32, _
                                                              ByRef _
                                                              lpMidiOutHdr As _
                                                              MIDIHDR, _
                                                              ByVal uSize As _
                                                              Int32) As Int32
 
Declare Function midiOutGetErrorText Lib "winmm.dll" Alias _
  "midiOutGetErrorTextA" ( _
  ByVal err As Int32, _
  ByVal lpText As String, _
  ByVal uSize As Int32) As Int32

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As _
  System.EventArgs) Handles Button1.Click
        Dim StreamHandle As Int32
        Dim xVal, zVal, Entfernung As Double
 
        midiStreamOpen(StreamHandle, Datenspeicher.PosXMidiPortID, 1, 0, 0, 0)
        Dim MidiEventx As New MIDIEVENT
        Dim DTIME As Int32 = 0
        Dim midout As New MIDIHDR
        Dim errortext As String = Space(128)
 
                MidiEventx.dwDeltaTime = 0
                MidiEventx.dwStreamID = 0
                MidiEventx.dwEvent = &H7F0B0000 'Bedeutet: 7F=Wert 127,0B= 
                ' Controllernummer11,00=Channel 0, 00= Shortmessage
                Dim myHandle = GCHandle.Alloc(MidiEventx, GCHandleType.Pinned)' 
                ' HIER IST DER FEHLER
                midout.lpData = myHandle.AddrOfPinnedObject.ToInt32
                midout.dwBufferLength = Marshal.SizeOf(midout.lpData)
                midout.dwBytesRecorded = Marshal.SizeOf(MidiEventx.dwEvent)
                midout.dwFlags = 0
                Dim midiheaderhandle = GCHandle.Alloc(midout, _
                  GCHandleType.Pinned)
                err = midiOutPrepareHeader(StreamHandle, midiheaderHandle, _
                Marshal.SizeOf(midout))
                midiOutGetErrorText(err, errortext, 128)
                midiStreamOut(StreamHandle, midout, Marshal.SizeOf(midout))
        err = midiStreamRestart(StreamHandle)
        err2 = midiStreamClose(StreamHandle)
    End Sub